To meet increasingly stringent diesel exhaust emissions requirements, original equipment manufacturers (OEMs) have introduced common rail fuel injection systems that develop pressures of up to 2000 bar (29,000 psi). In addition, fuel delivery schemes have become more complicated, often involving multiple injections per cycle. Containing higher pressures and allowing for precise metering of fuel require very tight tolerances within the injector. Such changes have made injectors more sensitive to fuel particulate contamination. Accordingly, injector performance concerns run across all segments; on-road fleets, mining equipment, farming equipment, railroad and inland marine engines.
There are two distinct types of deposits that have been identified on fuel injectors. One type of deposit is a hard carbonaceous deposit that is seen on the injector tips and on the outside of the fuel injectors. Such carbonaceous deposit is based on fuel degradation. The other type of deposit is a waxy, white to yellow deposit that appears as a thin film on the internal surfaces of high-pressure common rail (HPCR) injector needles and command plungers, primarily in the lowest clearance areas of the injector internals or on the pilot valve of the injectors.
If left untreated, the internal deposits may lead to significant power loss, reduced fuel economy, and, in extreme cases, increased downtime and higher maintenance costs due to premature replacement of “stuck injectors.” The internal deposits are believed to be a result of certain common corrosion inhibitors, biofuel components and acidic friction modifier, or other carboxylic components used in the fuel reacting with trace amounts of transition metals, alkali metal and alkaline earth metals causing salts that are relatively insoluble in ultra low sulfur diesel (ULSD) fuels compared to the better solubility of such salts in the higher sulfur fuels. The salts may be composed mainly of sodium salts of alkenyl succinic acids. Sodium can enter the diesel fuel from a number of sources including refinery salt drivers, storage tank water bottoms and seawater used as ship ballast. When such salts are present in fuel that is used in a High Pressure Common Rail (HPCR) engines, the salts may tend to deposit in the very tight tolerance areas of the injectors. Such deposits may lead to stuck fuel injectors or poor fuel injection, which in turn may lead to lost power, lost fuel economy, rough running engines, and eventually excessive vehicle downtime and maintenance expense.
In accordance with the disclosure, exemplary embodiments provide a fuel composition and method for cleaning up internal components of a fuel injector and for improving injector performance for a diesel engine. The composition includes major amount of middle distillate fuel having a sulfur content of 50 ppm by weight or less, and from about 1 to about 30 ppm by weight based on a total weight of fuel of a fuel soluble hydrocarbyl sulfonic acid or salt such as an alkyl aryl sulfonic acid or salt thereof, wherein the alkyl aryl sulfonic acid or salt thereof is effective to improve injector performance.
One embodiment of the disclosure provides a method of improving the injector performance of a fuel injected diesel engine including operating the diesel engine on a fuel composition comprising a major amount of diesel fuel having a sulfur content of 50 ppm by weight or less and a minor amount of an alkyl aryl sulfonic acid or salt thereof. The amount of alkyl aryl sulfonic acid or salt thereof in the fuel ranges from about 1 to about 30 ppm based on a total weight of the fuel.
Another embodiment of the disclosure provides a method of unsticking stuck fuel injectors of a fuel injected diesel engine. The method includes operating the diesel engine on a fuel composition comprising a major amount of diesel fuel having a sulfur content of 50 ppm by weight or less and from about 1 to about 30 ppm by weight based on a total weight of fuel of a fuel soluble alkyl aryl sulfonic acid or salt thereof.
A further embodiment of the disclosure provides a method cleaning up internal components of a fuel injector for a diesel engine. The method includes operating a fuel injected diesel engine on a fuel composition comprising a major amount of diesel fuel having a sulfur content of 50 ppm by weight or less and from about 1 to about 30 ppm by weight of a fuel soluble alkyl aryl sulfonic acid or salt thereof.
Another embodiment of the disclosure provides a method for reducing an amount of salt deposits on internal components of a fuel injector for a fuel injected diesel engine. The method includes operating the diesel engine on a fuel composition comprising a major amount of fuel and a minor amount of a fuel soluble alkyl aryl sulfonic acid or salt thereof.
An advantage of the fuel additive described herein is that the additive may not only reduce the amount of internal deposits forming on direct and/or indirect diesel fuel injectors, but the additive may also be effective to clean up dirty fuel injectors. The unexpected benefits of the fuel additive described herein is quite surprising since much higher treat rates are generally required for conventional detergents to be effective for cleaning up dirty fuel injectors.
Additional embodiments and advantages of the disclosure may be set forth in part in the detailed description which follows, and/or may be learned by practice of the disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.